Tuesday, 6 December 2011

I have recently discovered that .pdf documents can be uploaded or imported to Kindle. They do not display a front page image, but they are as readable as standard kindle documents. This is a convenient way of carrying lots of scientific papers around without the need to Internet access or a laptop. The system works well on kindle handheld or kindle for PC, which is how I processed these images. Of course, the conversion to kindle hand held reader looses all colour, but that is seldom an issue.

Technology is always moving on and I would expect with the new generation of readers, the colour loss will be corrected.

Thursday, 6 October 2011

The Jehol Biota contains probably the most prolific fossil producing strata in China. It is found within the Eastern Provinces, forming a complex and heavily folded sediment which shows poor conformity across the regions. For this reason, the dating and comparison of fossils is difficult at different geographical points in the sediments.

The associated rock formations are shown in the table, with the Jehol Biota marked with a blue background. There are 5 distinct stages across 6 rock formations, extending from 110Ma to about 138Ma ago.
These deposits, along with the Daohugou Beds, which sit stratigraphically below the Jehol levels have produced significant pterosaur specimens that have enhanced the understanding of this fossil group considerably.

Monday, 29 August 2011

There are lots of pterosaur toys on the market. Many of them are quite good, but there are a vast number of toys that are badly designed with respect to accuracy.

This model, from China, is of a mythical bat winged pterosaur with a strange head. As a toy it works well and it is fun to slot the bits together to assemble the final model.

A much more realistic model comes from Germany. Here a plastic Anhanguera has an appropriate stance and a good head reconstruction, based on prehistoric art work.

There are lots of slot together gliders made from polystyrene foam or similar soft plastics. This mini pteranodon was produced for the Natural History Museum, London. There are many more types available and thay all seem to fly quite well, being softand light enough to be relatively safe to use in confined spaces

Occasionally there is a different toy, like this jigsaw for younger children. With 20 pieces and a simple picture it is quite easy to assemble in its own wooden base frame.

There are also a multitude of snap together models of skeletons like this pteranodon in a jar kit. I have also seen glow in the dark skeleton models and Woodcraft do a self assembly fret saw wooden kit which is like a 3D jigsaw.
Add to this the rings, pendants, tee shirts and colouring books and the pterosaurs are well covered by the toy market. Here are a few links:

Friday, 8 July 2011

There have been many discussions and proposals about the function of the pterosaur head crest. They have ranged from display and sexual dimorphism to stability when dipping to feed in water and so on... Brian Roberts and Rick Lind of the University of Florida and Sankar Chatterjee of Texas Tech University have recently published work that suggests another option for the crest.

They have designed an aircraft with a variable position tail fin on the nose. This has been found to improve the efficiency of turning in flight. Such an aerodynamic option would be advantageous to pterosaurs in positioning themselves to feed whilst in flight. This option seems a sensible and practical explanation for the nature of the head crest as an aerodynamic feature associated with feeding. Biologically and in an evolutionary context, this is the best explanation I have heard to date.

PhysOrg.com - "By morphing and repositioning a small aircraft's vertical tail to resemble the cranial crest of a pterosaur, researchers have shown that the aircraft's turn radius can be reduced by 14%. The ability to make sharper turns is especially important for small aircraft that operate in urban environments and in the presence of obstacles."

Wednesday, 15 June 2011

Were pterosaurs in decline before the Extinction event at the end of the Cretaceous Era?

The answer to this question depends upon what is meant by decline. At the end of the Cretaceous there were a few species of large pterosaurs and no apparent small pterosaurs. Birds were more numerous and it is likely that small pterosaurs could not compete with the birds. The large pterosaurs seem to be very successful and show a wide ranging distribution.

If you apply the techniques used by Roup and Sepkosky to look at pterosaur survivorship, then this may give a clue. Below is a graph of pterosaur families for each of the main geological ages during the mesozoic.

Survivorship of pterosaurs at the family level

This graph shows that the pterosaur families increased to a peak in the Upper Jurassic and then reduced in number into the Cretaceous. The graph only includes pterosaurs where a family can be assigned with confidence.

If these data are applied to individual species, then a different shaped graph is seen.

Survivorship of pterosaurs at the species level

At the species level, the graph shows a peak in species numbers in the Lower Cretaceous and a fall in species numbers in the Upper Cretaceous.

It appears that pterosaurs, as an order of animals, were in decline before the great cretaceous extinction event. The success of the large pterosaurs is most likely a result of them being able to occupy niches that the birds are unable to exploit.

Tuesday, 31 May 2011

Today I chanced upon a young man and his mother. The lad was sporting a rather fine Tee Shirt with a pterosaur design. This immediately raised my awareness of the option to look at which pterosaur Tee shirts are available.

This particular example was produced by Mini Boden and after some investigation, it was found to be a limited production which is no longer available.

There are lots of pterosaur Tee Shirts on the market and a quick search on Google found hundreds of examples, mostly with cartoon representations or interesting mottos. These 3 caught my eye as being more to my own taste in Tee Shirts;

Monday, 23 May 2011

These photographs were taken by Brian Wickins who was part of the original team working on the George Whitfield Pteranodon flying model. The digital images were created from the original stills in 2006 and the copyright is from that time. My images here are copied in 2011 with permission.

The first photograph shows the Pteranodon model on a rig as a Concorde takes off. The aircraft in this picture is G-BBDG, Concorde 202 in the initial British Airways livery. The aircraft first flew at Filton on 13 Feb 1974 and was the fist Concorde to land at Heathrow on 6th July 1974. The initial speedbird livery was replaced in 1977. This gives the photograph a date frame.

The launch was a grand affair with lots of local interest. In 1974 most flying models were hand launched. Today it is more likely to see them air launched or launched from a cable tow or a ramp. This was an exceptionally large model to hand launch as it had a 7m wingspan and this was the first time such a large representation of a fossil animal had been attempted.

The third picture shows a view of the body cavity which contained the control kit. Batteries and servers were quite large at the time and imposed weight issues which had to be factored into the design.

Tuesday, 17 May 2011

As a rule, the pterosaur database is updated on a monthly basis. It has been quite some time since an update has been made as I have been involved in the UK National Census and have had little time to think about pterosaurs in the last 14 weeks.

A few new and varied pterosaur pages have been added or updated on the site. Over the past 3 years a vast amount of pterosaur information and new finds have come to light. When this type of thing happens, there is usually a following wind that merges new species into the existing framework. I suspect that future updates will not be long coming.

To enhance the presentation pages, a number of embedded videos have been included. The copyright and links to these web video clips is held by the originators and it is the first time that embedded content has been included on these pterosaur web pages.

Wednesday, 30 March 2011

On the 13th March this year I was contacted by Roger Bentley of the University of Reading who was involved in closing down an engineering company. He had in his possession the original flying pteranodon model used by George Whitfield to evaluate the findings of the Bramwell and Whitfield paper on the Biomechanics of Pteranodon.

The glider was designed to be an accurate representation of the Pterosaur, having a 7 meter wingspan. Wing movement was originally controlled by servers and wires which adjusted the wings and legs to give flexion to the fabric wing membrane. The model has some repairs where the structure was damaged or modified during test flights.

This was the first controllable flying model of a pterosaur and I thought this model had been destroyed in 1974, but it was dismantled in an attic store room, a little worse for wear.

After a few E-mails, Dave Martill took up the gauntlet and went to collect the model which is now residing at Portsmouth University, School of Earth and Environmental Sciences.

There are also some wonderful photographs of the tests, but I am unable to publish them without copyright permission.

Friday, 28 January 2011

A pterosaur find in 2009, from the Cretaceous deposits of Liouning Province in North Eastern China, has allowed sex determination in the pterosaur Darwinopterus. A number of specimens of this pterosaur are known and this recent find has revealed an uncrested individual with a ready to lay egg.

This pterosaur was fossilized after falling into the sea with a wing injury. The egg clearly makes this a female and as a result, it appears that all of the males sported cranial crests whilst the females were crestless. If this rule can be applied to other pterosaur species, it may be that many exhibit this type of sexual dimorphism.

Dr Charles Deeming of Lincoln University assisted in the analysis of the pterosaur fossil when it was in the UK. The fossil is currently held in the Zhejiang Museum of Natural History, Hangzhou, Zhejiang province, China.Lü L., Unwin D.M., Deeming D.C., Jin X., Liu Y. and Ji Q., 2011, An Egg-Adult Association, Gender, and Reproduction in Pterosaurs. Science 21 January 2011: Vol. 331 no. 6015 pp. 321- 324 DOI: 10.1126/science.1197323

Sunday, 16 January 2011

Pterosaur eggs are in the news again. A specimen egg in the collection of a texas enthusiast, Dr Neal Naranjo, has been scanned to reveal a pterosaur embryo inside. The egg is destined to be included in the collections of a new museum at Lufkin, Texas.

This is an unusual find and it will complement the previous finds from China and Argentina earlier this century. The images and location details have not yet been published, but when they are available, the study of pterosaur reproduction will be enhanced considerably. It is clear from the Chinese specimens that pterosaurs had eggs with thin leathery shells. The Argentine specimen was fossilised amongst juvenile animals which is a strong suggestion of birth and growth in colonies and it is apparent that pterosaurs were hatched with completely formed wings. Accepting that the shape and proportions of all of the known pterosaur eggs are similar, this small sample of 4 eggs is not enough information to look at variation over time. The published eggs all come from a period 100-130ma ago, which is a small time window in such a long evolutionary path.